Posting replies to Mac Rumors
I use mine for work mostly -- taking notes, storing and reviewing reference materials, showing mockups and prototypes to clients, etc.
I'm a wiki-holic, and use the iPad to update work and personal wikis. I use a personal wiki as a kind of GTD organizer for my various projects and to-dos. With the iPad I can basically add to or update any of the wikis where ever I'm at.
I use Numbers a lot, for invoicing, project timelines, expense tracking. I use Goodreader a lot for accessing various PDF and website archives. I use Pages now and then for contracts, and letters.
I also do most everything I did on my MacBook as far as music, video, web browsing, etc.
My iMac is still used for software and web developement. But I generally have the iPad open next to it, checking mockups, and updating wiki project entries as I go.
The iPad has really become a big part of my productivity tool kit.